The Frequency Dependence of AC Susceptibility at Variable Length of Bi-2223/Ag Tapes

An experimental investigation of ac susceptibility χ=χ'-jχ" of Bi-2223/Ag superconducting tapes with different length is performed at the perpendicular field. The influence of the length dimension on χ is analyzed with n-values deduced from the ac susceptibility scaling law. The results show that the normalized χ curves change significantly when the length is less than 4 cm and n-value calculated from those curves deceases from 12.5 to 5.5 compared with 19 from V(I) measurement. This is attributed to the transverse current distribution in silver with changing length and the contribution of this can be evaluated by n-values. The results can provide an important theoretical foundation for practical HTS applications.